why cant we store electricity indefinitely in batteries?
In: Chemistry
Here’s a simplified form of why we can’t do that.
When you learn about batteries in chemistry, a setup called the [galvanic cell/voltaic/electrochemical cell](https://www.chemicool.com/images/daniell-cell.png) is used to explain how a battery works.
We know that the transfer of electrons is more commonly known as electricity. In order for the flow of electrons to happen, we can use two different pieces of metal. If we use, say, something like Cobalt, which has a tendency to give away electrons to other metals in a battery, with something like Nickel, which wants the electrons, then we can create the flow of electrons from one metal to the other. If you look at the diagram, there is a flow of electrons from the Zinc to the Copper.
However, as electricity, or electrons, flow from one metal to the other, something interesting happens. When a metal is in its ground state, meaning it’s how you would find it normally, it is a solid, just like how we have Copper and Zinc metal. But when a metal loses its outermost, or valence electrons in transferring these electrons, it becomes an ion (since it now has a charge like Cu2+ or Zn2+) and will dissolve into the water/acid depending on what the battery uses. If we use the diagram with Copper and Zinc. With electrons going from the Zinc to the Copper, more of the Zinc metal (Zn) becomes Zn2+ and can dissolve into the solution. On the other hand, the Cu2+ in the water on the copper side gains electrons and become Cu metal. As the process goes on, the voltage produced by the battery drops and after enough time has passed, the battery will die as there are no more electrons that can be transferred.
As you can see, the battery cannot last forever because there are only a finite amount of electrons that can be transferred given a finite amount of metal and solution. Once all the electrons are transferred, you would have to run the reaction backwards (transfer it to the other side) by giving it power with another battery or power source. This is also essentially the same process that happens with your Phone or laptop’s battery. The Lithium-ion battery does essentially the same thing but is a bit different in its structure as it doesn’t use metal plates to facilitate a transfer of electrons. Your laptop has a bigger battery than your phone for example and so it’s capable of doing things like lasting longer at a higher voltage which is why your phone might stay on for 8 hours but a much higher wattage gaming laptop can run for as long as 3 hours even though it requires much much more electricity than your phone.
EDIT: With most batteries, there is also the issue of leakage and it’s due to the design of modern batteries such as the Lithium ion battery that it happens. Since our designs are not in perfect environments, environmental damage and leakage is bound to happen.
Time for some wibbly lines as we go back to the first modern batteries – the voltaic pile, developed by Volta. They were essentially a copper disc, on top of a zinc disc, on top of a piece of cardboard or felt soaked in salt water, repeated until you had the voltage you wanted.
As basic as that design is, you can see physical reasons why it won’t hold up forever – the electrolyte (salt water) will evaporate, the discs will corrode, reducing their contacting surfaces.
Our modern batteries suffer from similar problems, even ultramodern lithium ion rechargeable batteries, where the electrodes are damaged over time and use.
So, is it possible to store electricity indefinitely? Well, kind of yes, but only by cheating – going back to our stack, if we keep the discs separate and add electrolyte when we need it, then the battery is permanently charged – it just needs a little assembly before use.
You can, but the problem is that you would have to have a battery that isn’t physically hooked up together. It would either not be sealed (would dry out) or would be too large to make sense.
Batteries work by storing electrons between an electrolyte layer. That layer prevents the cathode from making contact with the anode, which would result in a short circuit. When a load is introduced to the battery, it pulls electrons from one side to the other, creating an electric current through the attached device.
What causes batteries to lose charge overtime is that the electrolyte is not perfect. Electrons will still slip past it and move to the anode layer, which means the batteries capacity is lowered.
When batteries are connected to electronics, they could also be powering part of the device, even if it’s turned off. IE: In phones, the battery will keep the real-time clock powered on, and possibly other components, while it’s turned off.
Because there is leakage, all our chemical and physical devices have small imperfections that allow small amounts of energy to be lost as heat.
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